1. Field of the Invention
The present invention relates generally to presses such as punch presses having an upper tool and a lower tool for processing sheet metals and other like workpieces and more particularly pertains to an improved tool holding apparatus for such presses whereby the tools can be positively held and easily attached and detached.
2. Description of the Prior Art
In presses such as punch presses for processing sheet metal and the like, the upper and lower tools have been held heretofore in various manners, but all of the conventional tool holding arrangements have had several inherent disadvantages. For example, in one conventional arrangement where an upper tool is held on a press by a collet means, it is difficult and troublesome to attach and detach the tool from the press. In another conventional arrangement where an upper tool is fixed to a press by a screw means, the upper tool cannot be securely held in place and is prone to loosen or detach itself from the press when it is stripped from a workpiece such as thick sheet metal after working the same. Also, in another conventional arrangement, an upper tool is formed with a flange to be held by a holding member which is in turn actuated by a suitable means such as a hydraulic motor. In this arrangement, the upper tool can be securely held and easily attached and detached, but such a tool holding apparatus is of course complicated and therefore costly. There have been problems also in holding the lower tools and there have been no means that meet all requirements for not only positively holding tools on presses but also easily attaching and detaching them onto and from presses.